app/{vmagent,vminsert}: follow-up after a1d1ccd6f2

- Document the change at docs/CHANGELOG.md
- Copy changes from docs/Single-server-VictoriaMetrics.md to README.md
- Add missing handler for processing multitenant requests ( https://docs.victoriametrics.com/vmagent/#multitenancy )
- Substitute github.com/stretchr/testify dependency with 3 lines of code in the added tests
- Comment unclear code at lib/protoparser/datadogsketches/parser.go , so @AndrewChubatiuk could update it
  and add permalinks to the original source code there.
- Various code cleanups

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5584
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3091

README.md

@@ -509,8 +509,9 @@ See also [vmagent](https://docs.victoriametrics.com/vmagent.html), which can be
 
 ## How to send data from DataDog agent
 
-VictoriaMetrics accepts data from [DataDog agent](https://docs.datadoghq.com/agent/) or [DogStatsD](https://docs.datadoghq.com/developers/dogstatsd/)
+VictoriaMetrics accepts data from [DataDog agent](https://docs.datadoghq.com/agent/), [DogStatsD](https://docs.datadoghq.com/developers/dogstatsd/) and
-via ["submit metrics" API](https://docs.datadoghq.com/api/latest/metrics/#submit-metrics) at `/datadog/api/v2/series` path.
+[DataDog Lambda Extension](https://docs.datadoghq.com/serverless/libraries_integrations/extension/)
+via ["submit metrics" API](https://docs.datadoghq.com/api/latest/metrics/#submit-metrics) at `/datadog/api/v2/series` or via "sketches" API at `/datadog/api/beta/sketches`.
 
 ### Sending metrics to VictoriaMetrics
 
@@ -536,10 +537,10 @@ add the following line:
 dd_url: http://victoriametrics:8428/datadog
 ```
 
-[vmagent](https://docs.victoriametrics.com/vmagent.html) also can accept Datadog metrics format. Depending on where vmagent will forward data,
+[vmagent](https://docs.victoriametrics.com/vmagent.html) also can accept DataDog metrics format. Depending on where vmagent will forward data,
 pick [single-node or cluster URL](https://docs.victoriametrics.com/url-examples.html#datadog) formats.
 
-### Sending metrics to Datadog and VictoriaMetrics
+### Sending metrics to DataDog and VictoriaMetrics
 
 DataDog allows configuring [Dual Shipping](https://docs.datadoghq.com/agent/guide/dual-shipping/) for metrics 
 sending via ENV variable `DD_ADDITIONAL_ENDPOINTS` or via configuration file `additional_endpoints`.
@@ -564,6 +565,19 @@ additional_endpoints:
   - apikey
 ```
 
+### Send metrics via Serverless DataDog plugin
+
+Disable logs (logs ingestion is not supported by VictoriaMetrics) and set a custom endpoint in `serverless.yaml`:
+
+```
+custom:
+  datadog:
+    enableDDLogs: false             # Disabled not supported DD logs
+    apiKey: fakekey                 # Set any key, otherwise plugin fails
+provider:
+  environment:
+    DD_DD_URL: <<vm-url>>/datadog   # VictoriaMetrics endpoint for DataDog
+```
 
 ### Send via cURL
 

app/vmagent/datadogsketches/request_handler.go

@@ -41,19 +41,15 @@ func insertRows(at *auth.Token, sketches []*datadogsketches.Sketch, extraLabels
 	tssDst := ctx.WriteRequest.Timeseries[:0]
 	labels := ctx.Labels[:0]
 	samples := ctx.Samples[:0]
-	for i := range sketches {
+	for _, sketch := range sketches {
-		sketch := sketches[i]
+		ms := sketch.ToSummary()
-		metrics := sketch.ToHistogram()
+		for _, m := range ms {
-		rowsTotal += sketch.RowsCount()
-		for m := range metrics {
-			metric := metrics[m]
 			labelsLen := len(labels)
 			labels = append(labels, prompbmarshal.Label{
 				Name:  "__name__",
-				Value: metric.Name,
+				Value: m.Name,
 			})
-			for l := range metric.Labels {
+			for _, label := range m.Labels {
-				label := metric.Labels[l]
 				labels = append(labels, prompbmarshal.Label{
 					Name:  label.Name,
 					Value: label.Value,
@@ -71,13 +67,13 @@ func insertRows(at *auth.Token, sketches []*datadogsketches.Sketch, extraLabels
 			}
 			labels = append(labels, extraLabels...)
 			samplesLen := len(samples)
-			for p := range metric.Points {
+			for _, p := range m.Points {
-				point := metric.Points[p]
 				samples = append(samples, prompbmarshal.Sample{
-					Timestamp: sketch.Dogsketches[p].Ts * 1000,
+					Timestamp: p.Timestamp,
-					Value:     point,
+					Value:     p.Value,
 				})
 			}
+			rowsTotal += len(m.Points)
 			tssDst = append(tssDst, prompbmarshal.TimeSeries{
 				Labels:  labels[labelsLen:],
 				Samples: samples[samplesLen:],

app/vmagent/main.go

@@ -613,6 +613,15 @@ func processMultitenantRequest(w http.ResponseWriter, r *http.Request, path stri
 		w.WriteHeader(202)
 		fmt.Fprintf(w, `{"status":"ok"}`)
 		return true
+	case "datadog/api/beta/sketches":
+		datadogsketchesWriteRequests.Inc()
+		if err := datadogsketches.InsertHandlerForHTTP(at, r); err != nil {
+			datadogsketchesWriteErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(202)
+		return true
 	case "datadog/api/v1/validate":
 		datadogValidateRequests.Inc()
 		// See https://docs.datadoghq.com/api/latest/authentication/#validate-api-key

app/vminsert/datadogsketches/request_handler.go

@@ -35,23 +35,18 @@ func insertRows(sketches []*datadogsketches.Sketch, extraLabels []prompbmarshal.
 	defer common.PutInsertCtx(ctx)
 
 	rowsLen := 0
-	for i := range sketches {
+	for _, sketch := range sketches {
-		sketch := sketches[i]
 		rowsLen += sketch.RowsCount()
 	}
 	ctx.Reset(rowsLen)
 	rowsTotal := 0
 	hasRelabeling := relabel.HasRelabeling()
-	for i := range sketches {
+	for _, sketch := range sketches {
-		sketch := sketches[i]
+		ms := sketch.ToSummary()
-		metrics := sketch.ToHistogram()
+		for _, m := range ms {
-		rowsTotal += sketch.RowsCount()
-		for m := range metrics {
-			metric := metrics[m]
 			ctx.Labels = ctx.Labels[:0]
-			ctx.AddLabel("", metric.Name)
+			ctx.AddLabel("", m.Name)
-			for l := range metric.Labels {
+			for _, label := range m.Labels {
-				label := metric.Labels[l]
 				ctx.AddLabel(label.Name, label.Value)
 			}
 			for _, tag := range sketch.Tags {
@@ -75,14 +70,13 @@ func insertRows(sketches []*datadogsketches.Sketch, extraLabels []prompbmarshal.
 			ctx.SortLabelsIfNeeded()
 			var metricNameRaw []byte
 			var err error
-			for p := range metric.Points {
+			for _, p := range m.Points {
-				value := metric.Points[p]
+				metricNameRaw, err = ctx.WriteDataPointExt(metricNameRaw, ctx.Labels, p.Timestamp, p.Value)
-				timestamp := sketch.Dogsketches[p].Ts * 1000
-				metricNameRaw, err = ctx.WriteDataPointExt(metricNameRaw, ctx.Labels, timestamp, value)
 				if err != nil {
 					return err
 				}
 			}
+			rowsTotal += len(m.Points)
 		}
 	}
 	rowsInserted.Add(rowsTotal)

docs/CHANGELOG.md

@@ -29,6 +29,7 @@ The sandbox cluster installation is running under the constant load generated by
 ## tip
 
 * FEATURE: all VictoriaMetrics components: add support for TLS client certificate verification at `-httpListenAddr` (aka [mTLS](https://en.wikipedia.org/wiki/Mutual_authentication)). See [these docs](https://docs.victoriametrics.com/#mtls-protection). See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5458).
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html) and [single-node VictoriaMetrics](https://docs.victoriametrics.com): add support for data ingestion via [DataDog lambda extension](https://docs.datadoghq.com/serverless/libraries_integrations/extension/) aka `/api/beta/sketches` endpoint. See [these docs](https://docs.victoriametrics.com/#how-to-send-data-from-datadog-agent) and [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3091). Thanks to @AndrewChubatiuk for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5584).
 * FEATURE: [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html): add `-disableReroutingOnUnavailable` command-line flag, which can be used for reducing resource usage spikes at `vmstorage` nodes during rolling restart. Thanks to @Muxa1L for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5713).
 * FEATURE: [dashboards/vmagent](https://grafana.com/grafana/dashboards/12683): add `Targets scraped/s` stat panel showing the number of targets scraped by the vmagent per-second.
 * FEATURE: [dashboards/all](https://grafana.com/orgs/victoriametrics): add new panel `CPU spent on GC`. It should help identifying cases when too much CPU is spent on garbage collection, and advice users on how this can be addressed.

docs/README.md

@@ -512,8 +512,9 @@ See also [vmagent](https://docs.victoriametrics.com/vmagent.html), which can be
 
 ## How to send data from DataDog agent
 
-VictoriaMetrics accepts data from [DataDog agent](https://docs.datadoghq.com/agent/) or [DogStatsD](https://docs.datadoghq.com/developers/dogstatsd/)
+VictoriaMetrics accepts data from [DataDog agent](https://docs.datadoghq.com/agent/), [DogStatsD](https://docs.datadoghq.com/developers/dogstatsd/) and
-via ["submit metrics" API](https://docs.datadoghq.com/api/latest/metrics/#submit-metrics) at `/datadog/api/v2/series` path.
+[DataDog Lambda Extension](https://docs.datadoghq.com/serverless/libraries_integrations/extension/)
+via ["submit metrics" API](https://docs.datadoghq.com/api/latest/metrics/#submit-metrics) at `/datadog/api/v2/series` or via "sketches" API at `/datadog/api/beta/sketches`.
 
 ### Sending metrics to VictoriaMetrics
 
@@ -539,10 +540,10 @@ add the following line:
 dd_url: http://victoriametrics:8428/datadog
 ```
 
-[vmagent](https://docs.victoriametrics.com/vmagent.html) also can accept Datadog metrics format. Depending on where vmagent will forward data,
+[vmagent](https://docs.victoriametrics.com/vmagent.html) also can accept DataDog metrics format. Depending on where vmagent will forward data,
 pick [single-node or cluster URL](https://docs.victoriametrics.com/url-examples.html#datadog) formats.
 
-### Sending metrics to Datadog and VictoriaMetrics
+### Sending metrics to DataDog and VictoriaMetrics
 
 DataDog allows configuring [Dual Shipping](https://docs.datadoghq.com/agent/guide/dual-shipping/) for metrics 
 sending via ENV variable `DD_ADDITIONAL_ENDPOINTS` or via configuration file `additional_endpoints`.
@@ -567,6 +568,19 @@ additional_endpoints:
   - apikey
 ```
 
+### Send metrics via Serverless DataDog plugin
+
+Disable logs (logs ingestion is not supported by VictoriaMetrics) and set a custom endpoint in `serverless.yaml`:
+
+```
+custom:
+  datadog:
+    enableDDLogs: false             # Disabled not supported DD logs
+    apiKey: fakekey                 # Set any key, otherwise plugin fails
+provider:
+  environment:
+    DD_DD_URL: <<vm-url>>/datadog   # VictoriaMetrics endpoint for DataDog
+```
 
 ### Send via cURL
 

docs/Single-server-VictoriaMetrics.md

@@ -520,8 +520,9 @@ See also [vmagent](https://docs.victoriametrics.com/vmagent.html), which can be
 
 ## How to send data from DataDog agent
 
-VictoriaMetrics accepts data from [DataDog agent](https://docs.datadoghq.com/agent/), [DogStatsD](https://docs.datadoghq.com/developers/dogstatsd/) or [DataDog Lambda Extension](https://docs.datadoghq.com/serverless/libraries_integrations/extension/)
+VictoriaMetrics accepts data from [DataDog agent](https://docs.datadoghq.com/agent/), [DogStatsD](https://docs.datadoghq.com/developers/dogstatsd/) and
-via ["submit metrics" API](https://docs.datadoghq.com/api/latest/metrics/#submit-metrics) at `/datadog/api/v2/series` path or via "sketches" API at `/datadog/api/beta/sketches`.
+[DataDog Lambda Extension](https://docs.datadoghq.com/serverless/libraries_integrations/extension/)
+via ["submit metrics" API](https://docs.datadoghq.com/api/latest/metrics/#submit-metrics) at `/datadog/api/v2/series` or via "sketches" API at `/datadog/api/beta/sketches`.
 
 ### Sending metrics to VictoriaMetrics
 
@@ -575,10 +576,10 @@ additional_endpoints:
   - apikey
 ```
 
+### Send metrics via Serverless DataDog plugin
 
-### Send via Serverless DataDog plugin
+Disable logs (logs ingestion is not supported by VictoriaMetrics) and set a custom endpoint in `serverless.yaml`:
 
-Disable logs (logs ingestion is not supported by Victoria Metrics) and set a custom endpoint in serverless.yaml
 ```
 custom:
   datadog:

go.mod

@@ -37,8 +37,6 @@ require (
 	gopkg.in/yaml.v2 v2.4.0
 )
 
-require github.com/stretchr/testify v1.8.4
-
 require (
 	cloud.google.com/go v0.112.0 // indirect
 	cloud.google.com/go/compute v1.23.4 // indirect
@@ -104,6 +102,7 @@ require (
 	github.com/prometheus/procfs v0.12.0 // indirect
 	github.com/rivo/uniseg v0.4.6 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/stretchr/testify v1.8.4 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	github.com/xrash/smetrics v0.0.0-20231213231151-1d8dd44e695e // indirect
 	go.opencensus.io v0.24.0 // indirect

lib/protoparser/datadogsketches/parser.go

@@ -9,6 +9,7 @@ import (
 )
 
 var (
+	// TODO: @AndrewChubatiuk, please provide a permalink for the original source code where these constants were extracted
 	epsillon   = 1.0 / 128
 	gamma      = 1 + 2*epsillon
 	gammaLn    = math.Log(gamma)
@@ -17,7 +18,16 @@ var (
 	quantiles  = []float64{0.5, 0.75, 0.9, 0.95, 0.99}
 )
 
-type label struct {
+var quantilesStr = func() []string {
+	a := make([]string, len(quantiles))
+	for i, q := range quantiles {
+		a[i] = strconv.FormatFloat(q, 'g', 3, 64)
+	}
+	return a
+}()
+
+// Label is a single label for Metric
+type Label struct {
 	Name  string
 	Value string
 }
@@ -25,8 +35,14 @@ type label struct {
 // Metric stores metrics extracted from sketches
 type Metric struct {
 	Name   string
-	Labels []label
+	Labels []Label
-	Points []float64
+	Points []Point
+}
+
+// Point stores a single point extracted from sketches
+type Point struct {
+	Value     float64
+	Timestamp int64
 }
 
 // SketchPayload stores sketches extracted from /api/beta/sketches endpoint
@@ -34,13 +50,15 @@ type Metric struct {
 //	message SketchPayload {
 //		 repeated Sketch sketches = 1
 //	}
+//
+// See https://github.com/DataDog/agent-payload/blob/38db68d9641c8a0bd2e1eac53b9d54793448850f/proto/metrics/agent_payload.proto#L90
 type SketchPayload struct {
 	Sketches []*Sketch
 }
 
-// UnmarshalProtobuf decodes byte array to SketchPayload struct
+// UnmarshalProtobuf decodes src to SketchPayload struct
 func (sp *SketchPayload) UnmarshalProtobuf(src []byte) (err error) {
-	sp.Sketches = sp.Sketches[:0]
+	sp.Sketches = nil
 	var fc easyproto.FieldContext
 	for len(src) > 0 {
 		src, err = fc.NextField(src)
@@ -51,13 +69,13 @@ func (sp *SketchPayload) UnmarshalProtobuf(src []byte) (err error) {
 		case 1:
 			data, ok := fc.MessageData()
 			if !ok {
-				return fmt.Errorf("cannot read SketchPayload sketches data")
+				return fmt.Errorf("cannot read Sketch data")
 			}
-			sp.Sketches = append(sp.Sketches, &Sketch{})
+			var s Sketch
-			s := sp.Sketches[len(sp.Sketches)-1]
 			if err := s.unmarshalProtobuf(data); err != nil {
-				return fmt.Errorf("cannot unmarshal sketch: %w", err)
+				return fmt.Errorf("cannot unmarshal Sketch: %w", err)
 			}
+			sp.Sketches = append(sp.Sketches, &s)
 		}
 	}
 	return nil
@@ -71,6 +89,8 @@ func (sp *SketchPayload) UnmarshalProtobuf(src []byte) (err error) {
 //	  repeated string tags = 4;
 //	  repeated Dogsketch dogsketches = 7
 //	}
+//
+// See https://github.com/DataDog/agent-payload/blob/38db68d9641c8a0bd2e1eac53b9d54793448850f/proto/metrics/agent_payload.proto#L91
 type Sketch struct {
 	Metric      string
 	Host        string
@@ -78,12 +98,12 @@ type Sketch struct {
 	Dogsketches []*Dogsketch
 }
 
-// unmarshalProtobuf decodes byte array to Sketch struct
+// unmarshalProtobuf decodes src to Sketch struct
 func (s *Sketch) unmarshalProtobuf(src []byte) (err error) {
 	s.Metric = ""
 	s.Host = ""
-	s.Tags = s.Tags[:0]
+	s.Tags = nil
-	s.Dogsketches = s.Dogsketches[:0]
+	s.Dogsketches = nil
 
 	var fc easyproto.FieldContext
 	for len(src) > 0 {
@@ -95,78 +115,87 @@ func (s *Sketch) unmarshalProtobuf(src []byte) (err error) {
 		case 1:
 			metric, ok := fc.String()
 			if !ok {
-				return fmt.Errorf("cannot read Sketch metric")
+				return fmt.Errorf("cannot read metric")
 			}
 			s.Metric = metric
 		case 2:
 			host, ok := fc.String()
 			if !ok {
-				return fmt.Errorf("cannot read Sketch host")
+				return fmt.Errorf("cannot read host")
 			}
 			s.Host = host
 		case 4:
 			tag, ok := fc.String()
 			if !ok {
-				return fmt.Errorf("cannot read Sketch tag")
+				return fmt.Errorf("cannot read tag")
 			}
 			s.Tags = append(s.Tags, tag)
 		case 7:
 			data, ok := fc.MessageData()
 			if !ok {
-				return fmt.Errorf("cannot read Sketch dogsketches data")
+				return fmt.Errorf("cannot read Dogsketch data")
 			}
-			s.Dogsketches = append(s.Dogsketches, &Dogsketch{})
+			var d Dogsketch
-			d := s.Dogsketches[len(s.Dogsketches)-1]
 			if err := d.unmarshalProtobuf(data); err != nil {
-				return fmt.Errorf("cannot unmarshal dogsketch: %w", err)
+				return fmt.Errorf("cannot unmarshal Dogsketch: %w", err)
 			}
+			s.Dogsketches = append(s.Dogsketches, &d)
 		}
 	}
 	return nil
 }
 
-// RowsCount calculates generated rows num from sketch
+// RowsCount returns the number of samples s generates.
 func (s *Sketch) RowsCount() int {
-	return (len(quantiles) + len(s.extractAggr())) * len(s.Dogsketches)
+	// The sketch contains len(quantiles) plus *_sum and *_count metrics
+	// per each Dogsketch in s.Dogsketches.
+	return (len(quantiles) + 2) * len(s.Dogsketches)
 }
 
-func (s *Sketch) extractAggr() []*Metric {
+// ToSummary generates Prometheus summary from the given s.
-	return []*Metric{
+func (s *Sketch) ToSummary() []*Metric {
-		{
+	metrics := make([]*Metric, len(quantiles)+2)
-			Name:   s.Metric + "_sum",
-			Labels: []label{},
-			Points: make([]float64, len(s.Dogsketches)),
-		}, {
-			Name:   s.Metric + "_count",
-			Labels: []label{},
-			Points: make([]float64, len(s.Dogsketches)),
-		},
-	}
-}
-
-// ToHistogram generates histogram metrics
-func (s *Sketch) ToHistogram() []*Metric {
 	dogsketches := s.Dogsketches
-	aggr := s.extractAggr()
+
-	metrics := make([]*Metric, len(quantiles))
+	sumPoints := make([]Point, len(dogsketches))
-	for q := range quantiles {
+	countPoints := make([]Point, len(dogsketches))
-		quantile := quantiles[q]
+	metrics[len(metrics)-2] = &Metric{
-		metrics[q] = &Metric{
+		Name:   s.Metric + "_sum",
+		Points: sumPoints,
+	}
+	metrics[len(metrics)-1] = &Metric{
+		Name:   s.Metric + "_count",
+		Points: countPoints,
+	}
+
+	for i, q := range quantiles {
+		points := make([]Point, len(dogsketches))
+		for j, d := range dogsketches {
+			timestamp := d.Ts * 1000
+			points[j] = Point{
+				Timestamp: timestamp,
+				Value:     d.valueForQuantile(q),
+			}
+			sumPoints[j] = Point{
+				Timestamp: timestamp,
+				Value:     d.Sum,
+			}
+			countPoints[j] = Point{
+				Timestamp: timestamp,
+				Value:     float64(d.Cnt),
+			}
+		}
+		metrics[i] = &Metric{
 			Name: s.Metric,
-			Labels: []label{{
+			Labels: []Label{{
 				Name:  "quantile",
-				Value: strconv.FormatFloat(quantile, 'g', 3, 64),
+				Value: quantilesStr[i],
 			}},
-			Points: make([]float64, len(dogsketches)),
+			Points: points,
-		}
-		for d := range dogsketches {
-			dogsketch := dogsketches[d]
-			aggr[0].Points[d] = dogsketch.Sum
-			aggr[1].Points[d] = float64(dogsketch.Cnt)
-			metrics[q].Points[d] = dogsketch.pointForQuantile(quantile)
 		}
 	}
-	return append(metrics, aggr...)
+
+	return metrics
 }
 
 // Dogsketch proto struct
@@ -180,6 +209,8 @@ func (s *Sketch) ToHistogram() []*Metric {
 //	  repeated sint32 k = 7;
 //	  repeated uint32 n = 8;
 //	}
+//
+// See https://github.com/DataDog/agent-payload/blob/38db68d9641c8a0bd2e1eac53b9d54793448850f/proto/metrics/agent_payload.proto#L104
 type Dogsketch struct {
 	Ts  int64
 	Cnt int64
@@ -190,91 +221,102 @@ type Dogsketch struct {
 	N   []uint32
 }
 
-// unmarshalProtobuf decodes byte array to Dogsketch struct
+// unmarshalProtobuf decodes src to Dogsketch struct
 func (d *Dogsketch) unmarshalProtobuf(src []byte) (err error) {
 	d.Ts = 0
 	d.Cnt = 0
 	d.Min = 0.0
 	d.Max = 0.0
 	d.Sum = 0.0
-	d.K = d.K[:0]
+	d.K = nil
-	d.N = d.N[:0]
+	d.N = nil
+
 	var fc easyproto.FieldContext
 	for len(src) > 0 {
 		src, err = fc.NextField(src)
 		if err != nil {
-			return fmt.Errorf("cannot read next field in Dogsketch message, %w", err)
+			return fmt.Errorf("cannot read next field in Dogsketch message: %w", err)
 		}
 		switch fc.FieldNum {
 		case 1:
 			ts, ok := fc.Int64()
 			if !ok {
-				return fmt.Errorf("cannot read Dogsketch timestamp")
+				return fmt.Errorf("cannot read timestamp")
 			}
 			d.Ts = ts
 		case 2:
 			cnt, ok := fc.Int64()
 			if !ok {
-				return fmt.Errorf("cannot read Dogsketch count")
+				return fmt.Errorf("cannot read count")
 			}
 			d.Cnt = cnt
 		case 3:
 			min, ok := fc.Double()
 			if !ok {
-				return fmt.Errorf("cannot read Dogsketch min")
+				return fmt.Errorf("cannot read min")
 			}
 			d.Min = min
 		case 4:
 			max, ok := fc.Double()
 			if !ok {
-				return fmt.Errorf("cannot read Dogsketch max")
+				return fmt.Errorf("cannot read max")
 			}
 			d.Max = max
 		case 6:
 			sum, ok := fc.Double()
 			if !ok {
-				return fmt.Errorf("cannot read Dogsketch sum")
+				return fmt.Errorf("cannot read sum")
 			}
 			d.Sum = sum
 		case 7:
 			var ok bool
 			d.K, ok = fc.UnpackSint32s(d.K)
 			if !ok {
-				return fmt.Errorf("cannot read Dogsketch k")
+				return fmt.Errorf("cannot read k")
 			}
 		case 8:
 			var ok bool
 			d.N, ok = fc.UnpackUint32s(d.N)
 			if !ok {
-				return fmt.Errorf("cannot read Dogsketch n")
+				return fmt.Errorf("cannot read n")
 			}
 		}
 	}
 	return nil
 }
 
-func (d *Dogsketch) pointForQuantile(quantile float64) float64 {
+func (d *Dogsketch) valueForQuantile(q float64) float64 {
 	switch {
 	case d.Cnt == 0:
 		return 0
-	case quantile <= 0:
+	case q <= 0:
 		return d.Min
-	case quantile >= 1:
+	case q >= 1:
 		return d.Max
 	}
 
-	rank := quantile * float64(d.Cnt-1)
+	ns := d.N
-	nLen := len(d.N)
+	ks := d.K
-	for cnt, i := 0.0, 0; i < nLen; i++ {
+	if len(ns) != len(ks) {
-		cnt += float64(d.N[i])
+		// Avoid index out of range panic in the loop below.
+		return 0
+	}
+
+	rank := q * float64(d.Cnt-1)
+	cnt := float64(0)
+	for i, n := range ns {
+		cnt += float64(n)
 		if cnt <= rank {
 			continue
 		}
-		weight := (cnt - rank) / float64(d.N[i])
+		weight := (cnt - rank) / float64(n)
-		vLow := f64(d.K[i])
+		vLow := f64(ks[i])
 		vHigh := vLow * gamma
 		switch i {
-		case nLen:
+		// TODO: I'm unsure this code is correct. i cannot equal len(ns) in this loop.
+		// @AndrewChubatiuk, please add a permalink to the original source code, which was used
+		// for writing this code, in the comments to this function.
+		case len(ns):
 			vHigh = d.Max
 		case 0:
 			vLow = d.Min
@@ -288,6 +330,8 @@ func f64(k int32) float64 {
 	switch {
 	case k < 0:
 		return -f64(-k)
+	// TODO: I'm unsure this logic is correct, since k can be smaller than math.MinInt16 and bigger than math.MaxInt16
+	// @AndrewChubatiuk, please add a permalink to the original source code, which was used for writing this code.
 	case k == math.MaxInt16 || k == math.MinInt16:
 		return math.Inf(int(k))
 	case k == 0:

lib/protoparser/datadogsketches/parser_test.go

@@ -1,16 +1,17 @@
 package datadogsketches
 
 import (
+	"math"
 	"testing"
-
-	"github.com/stretchr/testify/assert"
 )
 
 func TestPointsForQuantile(t *testing.T) {
-	f := func(d *Dogsketch, quantile float64, expected float64) {
+	f := func(d *Dogsketch, q float64, vExpected float64) {
 		t.Helper()
-		point := d.pointForQuantile(quantile)
+		v := d.valueForQuantile(q)
-		assert.InDelta(t, point, expected, 0.5)
+		if math.Abs(v-vExpected) > 0.4 {
+			t.Fatalf("unexpected value; got %v; want %v", v, vExpected)
+		}
 	}
 	sketches := &Dogsketch{
 		Min: 8.0,

lib/protoparser/datadogsketches/stream/streamparser.go

@@ -20,7 +20,6 @@ import (
 //
 // callback shouldn't hold series after returning.
 func Parse(r io.Reader, contentEncoding string, callback func(series []*datadogsketches.Sketch) error) error {
-	var err error
 	wcr := writeconcurrencylimiter.GetReader(r)
 	defer writeconcurrencylimiter.PutReader(wcr)
 	r = wcr
@@ -50,18 +49,17 @@ func Parse(r io.Reader, contentEncoding string, callback func(series []*datadogs
 	req := getRequest()
 	defer putRequest(req)
 
-	err = req.UnmarshalProtobuf(ctx.reqBuf.B)
+	if err := req.UnmarshalProtobuf(ctx.reqBuf.B); err != nil {
-	if err != nil {
 		unmarshalErrors.Inc()
-		return fmt.Errorf("cannot unmarshal DataDog request with size %d bytes: %w", len(ctx.reqBuf.B), err)
+		return fmt.Errorf("cannot unmarshal DataDog Sketches request with size %d bytes: %w", len(ctx.reqBuf.B), err)
 	}
 
 	rows := 0
 	sketches := req.Sketches
-	for i := range sketches {
+	for _, sketch := range sketches {
-		rows += len(sketches[i].Dogsketches)
+		rows += sketch.RowsCount()
 		if *datadogutils.SanitizeMetricName {
-			sketches[i].Metric = datadogutils.SanitizeName(sketches[i].Metric)
+			sketch.Metric = datadogutils.SanitizeName(sketch.Metric)
 		}
 	}
 	rowsRead.Add(rows)

lib/protoparser/datadogv1/stream/streamparser.go

@@ -40,6 +40,7 @@ func Parse(r io.Reader, contentEncoding string, callback func(series []datadogv1
 		defer common.PutZlibReader(zlr)
 		r = zlr
 	}
+
 	ctx := getPushCtx(r)
 	defer putPushCtx(ctx)
 	if err := ctx.Read(); err != nil {
@@ -47,10 +48,12 @@ func Parse(r io.Reader, contentEncoding string, callback func(series []datadogv1
 	}
 	req := getRequest()
 	defer putRequest(req)
+
 	if err := req.Unmarshal(ctx.reqBuf.B); err != nil {
 		unmarshalErrors.Inc()
 		return fmt.Errorf("cannot unmarshal DataDog POST request with size %d bytes: %w", len(ctx.reqBuf.B), err)
 	}
+
 	rows := 0
 	series := req.Series
 	for i := range series {